2014-03-07_REVISION - M1988112 (3)

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8700 P8800 8500 8400 -f 0 r fl 100 200 300 400 500 600 DISTANCE - FEET MATERIAL PROPERTIES MATERIAL TYPE MATERIAL DESCRIPTION UWT WT (DS1) $NEAR STRENGTH a aA1 e dp C Dst UNSATURATED TAKMG$ 105 120 30 300 112 SATURATED THINGS • 105 120 16 300 EUSANKMENT FIL 125 135 35 0 v FOUNDATION 504. 125 135 35 0 STAaK Y ANALYSIS SUMMARY FAILURE TYPE STATRC F05 8700 YIELD ACCn. (R g) 8600 1.31 W UM ® 162 2.76 112 Z a 2.67 8500 �y 10.6 8400 700 800 900 STAaK Y ANALYSIS SUMMARY FAILURE TYPE STATRC F05 PSCVMTATC FOS' YIELD ACCn. (R g) 2.87 1.31 W UM NA 162 2.76 112 15.2 a 2.67 1.12 10.6 6.9 1.95 11.3 •IL9 /N M: orr.O ACMUW = RKOWOMro N A cwx AMOtl 6P TEW M CO[n'Ot>r' p 011♦ MID 11! YI coley U / S.."" W-03. M - . APKr %Z W ,Ny /*JAIL $"A" (Reproduced from SRK, 1995) Figure 5 Results of Downstream Stability Analyses 3.1.3 Monitoring Data Monthly monitoring reports were reviewed for available data on the embankment standpipe piezometers. Data indicate the piezometers are dry or have a slight amount of water in the bottom of the casing that could be related to condensation or trapped water in the end cap of the casing. Monitoring data indicate there is no reason to believe there is an elevated phreatic surface above the liner along the axis of the main dam. This would indicate the drain layer above the liner is functioning as intended. As described later, the pipe outlets of the underdrain system had become temporarily blocked by surface sloughing and erosion sediment deposition at the toe of the dam, but the piezometers do not indicate this has resulted in an elevated phreatic surface at the location of the piezometers. The blocked outfalls were cleared (exposed) before the May 13, 2013 inspection. 3.2 VISUAL ASSESSMENT OF DAM STABILITY The findings of issues identified in the two 2013 site visits and the ISI are summarized in the following sections. San Luis Project Miller Geotechnical Consultants Tailing Dam Data Report 10 February 2014